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Fake Antivirus- Journey from Trojan
to a Persistent Threat
DeepSec 2011 Jagadeesh Chandraiah
DeepSec 2011
Agenda
• FakeAV Trends
• Infection Vectors
• Packer Evolution
• How do they work ?
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Introduction Fake AntiVirus (FakeAV) is a malware which displays fake warnings to the users to trick them to buy illegitimate software.
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Introduction
FakeAV Trends
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Analyse the major events over the last three and half years.
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• Dramatic Rise of FakeAV in 2009
• Black Hat SEO was heavily used.
• Popular websites were used to serve FakeAV. • ex: New York Times news paper Website in 2009.
• Government Embassy website Attacks.
• Social Networking Sites were used (Facebook and Twitter).
FakeAV Trends
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• More Spam redirects to FakeAV.
• More unpatched PDF and Java Vulnerabilities were used to deliver FakeAV.
• Black Hat SEO on hot topics, still remained the popular infection method.
FakeAV Trends 2010 continued to see the spike in FakeAV detections.
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• Mac users were infected with Mac Defender in big scale around May
2011.
FakeAV Trends Significant events in 2011.
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• Sharp Decline in FakeAV detections, due to law enforcement actions in
Aug 2011.
Sharp Decline Significant events in 2011.
Sharp Decline
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● ChronoPay’s server were compromised and details were reported online.
● Several FakeAV programs had credit card processing issues.
FakeAV is down, but still active
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Sophos Top Five FakeAV Detection rate between Mar-Oct 2011.
FakeAV is down, but still active
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FakeAV infection between 1st Quarter of 2010 and 2nd Quarter of 2011, according to Microsoft Security Intelligence Report.
Infection Methods
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We will analyse popular Infection methods and how they work.
Black Hat SEO
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Poisoning search engine optimization.
• Illegitimate way of increasing search engine ranking.
Black Hat SEO Pictorial Representation of Black Hat SEO attack
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Black Hat SEO
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• Step1: Identify and compromise legitimate websites. • Step2: Upload multifunctional PHP script to the compromised website.
• Step3: Feed crawlers with specially stuffed webpage with keywords.
• Step4: Redirect users coming through search engine to FakeAV website.
Malvertising
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Serving FakeAV through Advertising networks.
Malvertising JavaScript used in New York Times newspaper website.
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Cold Calling
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Fake tech support centre’s are used to scam users.
Spam Campaigns
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FakeAV served through email attachments and drive by download links.
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Spam Campaigns
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Fake Codecs Users are social engineered to download FakeAV as Codecs.
Exploit Kit
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Use Blackhole Exploit kit as an example to see how exploit kit works.
Exploit Kit Black Hole Exploit Kit panel showing Infections by country and vulnerabilities.
Exploit kit Blacklisting mechanism used by Black Hole.
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Exploit Kit Infection mechanism using Exploit kit.
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Exploit Kit Obfuscated Black Hole Exploit Script
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Decrypted Exploit script checking version and creating Iframe element.
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Exploit Kit
Packer Evolution
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• Anti Emulation API
• Process Environment Block
• Thread Information Block
• Kuser Shared Data
FakeAV without packed layer
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Packer Evolution
Anti Emulation
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• Emulator is a piece of Software used to simulate the behaviour of a system.
• Windows X86 emulator is used to simulate the behaviour of X86 processor.
• Malware authors use tricks to break emulation.
Anti Emulation API
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Anti Emulation API
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FS:30
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Process Environment Block
FS:18
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Thread Information Block
KUSER_SHARED_DATA
● Usually mapped at 0x7FFE0000
● Checking the presence of value at 0x7FFE0004 (TickCountMultiplier).
● Values at this structure are also known to be used in obfuscated calls and decryption strings.
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Understand Packing using a Polymorphic Cryptor.
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How is this Done ?
Click icon to add table
Packer Evolution Cryptors available in underground forums.
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Packer Evolution Crum Polymorphic Cryptor
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Packer Evolution. Crum Polymorphic Cryptor with different icons.
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Packer Evolution
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Testing Crum Polymorphic Cryptor
Packer Evolution
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Testing Crum Polymorphic Cryptor
Packer Evolution
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Anti Emulation stuff inserted by Crum Polymorphic Cryptor
What Drives FakeAV ?
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What Drives FakeAV ?
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What Drives FakeAV ?
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What Drives FakeAV ?
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• FakeAV developers use affiliate networks to distribute and advertise FakeAV.
• Affiliates in turn recruit meta affiliates to distribute FakeAV links and binaries.
• Money is paid in Pay per Install scheme, for driving traffic to FakeAV Landing Pages and FakeAV purchases.
• University of California research study reveals that FakeAV business earned more than 130 million dollars.
AV vs FakeAV
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Conclusion
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• FakeAV is still one of the big threats actively infecting users.
• Better understanding of operations used.
• Able to study the different tricks used by FakeAV code. • Use this knowledge to better protect users from FakeAV Infection.
Acknowledgements
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